Comparison of Two-Level Cervical Disc Replacement Versus Two-Level Anterior Cervical Discectomy and Fusion in the Outpatient Setting

Matthew K. Doan, BS; Andrew S. Chung, MD; Justin L. Makovicka, MD; Jeffrey D. Hassebrock, MD; Thomas M. Polveroni, BA; Karan A. Patel, MD


Spine. 2021;46(10):658-664. 

In This Article

Abstract and Introduction


Study Design: Retrospective cohort study.

Objective: The aim of this study was to evaluate the safety of two-level cervical disc replacement (CDR) in the outpatient setting.

Summary of Background Data: Despite growing interest in CDR, limited data exist evaluating the safety of two-level CDR in the outpatient setting.

Methods: The National Surgical Quality Improvement Program (NSQIP) database was queried for all two-level anterior cervical discectomy and fusion (ACDF) and CDR procedures between 2015 and 2018. Demographics, comorbidities, and 30-day postoperative complication rates of outpatient two-level CDR were compared to those of inpatient two-level CDR and outpatient two-level ACDF. Radiographic data are not available in the NSQIP.

Results: A total of 403 outpatient CDRs were compared to 408 inpatient CDRs and 4134 outpatient ACDFs. Outpatient CDR patients were older and more likely to have pulmonary comorbidities compared to inpatient CDR (P < 0.03). Outpatient CDR patients were less likely to have an American Society of Anesthesiologists class ≥2 and have hypertension compared to outpatient ACDF patients (P < 0.0001). Outpatient CDR had a lower 30-day readmission rate (0.5% vs. 2.5%, P = 0.02) and lower 30-day reoperation rate (0% vs. 1%, P = 0.047) compared to inpatient CDR. Outpatient CDR had a lower readmission rate (0.5% vs. 2.1%, P = 0.03) compared to outpatient ACDF, but there was no difference in reoperation rates between the two procedures (0% vs. 0.8%, P = 0.07). Outpatient CDR had an overall complication rate of 0.2%, inpatient CDR had a complication rate of 0.9%, and outpatient ACDF had a complication rate of 1.3%. These differences were not significant.

Conclusion: To our knowledge, this is the largest multicenter study examining the safety of two-level outpatient CDR procedures. Outpatient two-level CDR was associated with similarly safe outcomes when compared to inpatient two-level CDR and outpatient two-level ACDF. This suggests that two-level CDR can be performed safely in the outpatient setting.

Level of Evidence: 3


In the United States, cervical disc replacement (CDR) has grown in popularity over the past decade. From 2009 to 2015, CDR increased in utilization at a rate of 17% per year without any evidence of plateauing.[2] As the population continues to age, the demand for cervical spine surgery, including CDR, will continue to increase as the incidence of symptomatic cervical spine disease continues to rise.[37]

Anterior cervical discectomy and fusion (ACDF) and CDR provide a means for effective discectomy, restoration of disc space height, and decompression of spinal stenosis.[1,2] Many studies, including several meta analyses, have shown that both procedures have similarly good outcomes for the treatment of degenerative cervical disc disease.[3–8] Research also shows that single and multilevel CDR procedures are safe compared to ACDF.[3,5,9] One advantage of CDR is the potential for preserved range of motion in the long term.[10] This preservation of motion could theoretically reduce the intradiscal pressure at adjacent levels thereby lowering the incidence of adjacent segment disease, a common complication that affects up to 25.6% of ACDF patients within 10 years.[28] Koreckij et al[29] suggest that there is evidence showing lower rates of revision surgery due to adjacent segment disease in patients treated with CDR compared to ACDF, particularly in two-level procedures.

As the volume of spine surgeries continues to grow, many procedures are now performed in an outpatient setting. This trend can be attributed to the decreasing invasiveness of surgery, patients' desire to spend less time in the hospital, and significant cost benefits. These factors all contribute to increased value-based care.[11] The progressive transition toward ambulatory care has fostered significant research interest in the comparison of clinical outcomes and safety profiles between outpatient and inpatient procedures.[11] Several studies have found outpatient one- two-level ACDF to be safe, with low complication rates comparable to inpatient ACDF.[32–35] Recently, outpatient single-level CDR has also been found to yield similarly good outcomes compared to inpatient single-level CDR.[26]

Despite the growing trend of performing CDR in the outpatient setting,[2] to our knowledge, no previous study has compared the safety of outpatient two-level CDR to two-level ACDF on a large scale. Furthermore, beyond the published Food and Drug Administration (FDA) Investigational Device Exemption (IDE) studies,[31,36] the current evidence regarding the safety of outpatient two-level CDR is limited. Therefore, the purpose of this study is to analyze the safety of outpatient two-level CDR compared to inpatient two-level CDR and outpatient two-level ACDF through a national, multicenter database.